INTRODUCTION:Aspergillus empyema is an uncommon entity occurring as a complication of pneumonectomy or a bronchopleural fistula due to cavitary lung disease. In the former, the pathogenesis is usually related to bronchial stump silk suture infection with subsequent pleural spread. There are no reports describing methylmethacrylate serving as a nidus for Aspergillus infection. We describe a case of an infected methylmethacrylate chest wall construct with Aspergillus fumigatus and empyema necessitans.
CASE PRESENTATION:A 45 year old white male had a history of a localized right chest wall chondrosarcoma treated with local resection and methylmethacrylate reconstruction in 1994. He received no radiation or chemotherapy and remained in remission. Twelve years later he presented with cellulitis and abscess formation of his right chest wall with systemic symptoms, weight loss of 30 pounds and purulent cough for two weeks. He was a lifelong non-smoker, non-drinker and had no history of pulmonary disease or recent chest trauma. He had no history of HIV, diabetes or recurrent infections suggesting immunodeficiency. He recently vacated a moldy trailer but had no other definitive exposure history. On examination he was febrile with right chest wall erythema, flunctuance and crepitus. CT imaging revealed multiple subcutaneous nodules with a 2 × 5cm subcutaneous complex mass containing gas and fluid surrounding the mesh with extension into the pleural space superiorly. Two indeterminate right middle lobe nodules and patchy infiltrates were present with right axillary, hilar and mediastinal lymphadenopathy. Broad spectrum antibiotics were started but both sputum and aspirate cultures were positive for only Aspergillus fumigatus. Voriconazole monotherapy was initiated and the wound was incised and drained in the operating room where a small bronchopleural fistula was sealed. Multiple surgical specimens were benign. Although voriconazole was continued at 200mg BID with gradual improvement of symptoms and adequate wound healing, repeat imaging revealed incomplete resolution and persistence of a subcutaneous abscess requiring further percutaneous drainage.
DISCUSSIONS:Aspergillus empyema usually results from pleural inoculation in patients with bronchopleural fistulas where endobronchial Aspergillus enters the pleural space through the fistula. In the post-pneumonectomy patient, bronchial stump infection is rare with less than 30 reported cases. Most involve wounds with silk rather than nylon suture material and none are described with stainless steel sutures. The high capillarity of the silk favors progression of infection in contrast to the other materials. Typically such patients do not have underlying Aspergillus lung disease. Cure is achieved by removal of the infected foreign body and systemic, but not pleural, antifungal therapy for those cases with tissue invasion or immunosuppression. Voriconazole has replaced amphotericin as first line therapy with caspofungin available for combination salvage therapy. Although methylmethacrylate prostheses provide excellent chest wall stability and lessen the risk of post-operative respiratory complications, they may be associated with a greater number of bacterial wound complications but none with Aspergillus have been described. Some reports suggest that if removal of the foreign material can be delayed by several weeks, a strong fibrous layer will be formed that is rigid enough to provide chest wall stability. At present our patient remains on voriconazole and is contemplating delayed mesh removal.
CONCLUSION:This case highlights that Aspergillus can be a delayed complication of prosthetic chest wall reconstruction. Its rarity is likely due to methylmethacrylate’s non porous nature and low capillarity. Issues for further discussion include the need for mesh removal based on experiences with bronchial stump Aspergillosis and the mechanism of infection-whether the infection started in the pulmonary parenchyma with subsequent pleural and then chest wall extension or vice versa.
DISCLOSURE:Rael Sundy, No Financial Disclosure Information; No Product/Research Disclosure Information